Method for managing defective area of optical recording medium

ABSTRACT

A storage medium and method for managing a defective area of the storage medium are provided. The method includes (A) identifying a defective area found during recording or reproducing of data; (B) writing the data intended for the defective area in any part of a user area that is unused, wherein the storage medium is without any pre-designated spare area so that the entire user area corresponds to an entire data area of the storage medium; and (C) writing positional information about the defective area in the user area.

This application is a continuation of application Ser. No. 10/375,128filed on Feb. 28, 2003 now U.S. Pat. No. 6,901,041, which is acontinuation of now patented application Ser. No. 09/404,303, filed onSep. 24, 1999 (U.S. Pat. No. 6,529,458) the entire contents of each ofthese applications are hereby incorporated by reference and for whichpriority is claimed under 35 U.S.C. § 120; and this application claimspriority of Application No. 40144/1998 filed in Korea on Sep. 26, 1998under 35 U.S.C. § 119.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rewritable optical recording mediumsystem, and more particularly, to the associated method for managing adefective area on an optical recording medium.

2. Discussion of the Related Art

In general, in the optical recording media, there are a ROM type forread only, a WORM type for writing once, and a rewritable type forrepetitive writing. In the ROM type optical recording media, there areCD-ROM (Compact and the like, and, in the WORM type optical recordingmedium, there are CD-R (Recordable Compact Disc) which permits one timewriting, DVD-R (Recordable Digital Versatile Disc) which permits onetime writing, and the like. And, in disks which are rewritable freelyand repetitively, there are CD-RW (Rewritable Compact Disc), andrewritable digital versatile disc (DVD-RAM, DVD-RW).

In rewritable optical disks, information writing/readingthereto/therefrom is done repetitively. The repetitive write/read ofinformation causes a change in a ratio of components, i.e., the mixture,that form a recording layer (provided for recording information), froman initial mixing ratio. This leads to a loss in the initial propertiesof the mixture, and that causes errors to occur in writing/readinginformation. This overall process is called degradation.

Areas of degradation are identified as defective areas when formatting,or when executing a write or read command for the optical disk. Otherthan by degradation, defective areas of the rewritable optical disk arecaused by scratch on a surface, dust particles, and/or from productiondefects. To prevent writing/reading data to/from the defective areasformed by the foregoing causes, management of the defective areas isrequired.

As shown in FIG. 1, DMA's (Defect Management Areas) are provided in alead-in area and in a lead-out area of the optical recording medium formanaging the defective areas of the optical recording medium. Data areasare managed in zones (or groups), each having a user area for use inactual writing of data and a spare area to prove replacement capacity inthe case of defects in the user area. In general, there are four DMAsprovided in one disk (for example, a DVD-RAM), two in the lead-in areaand the other two in the lead-out area.

As management of the DMAs is important, the same data is repeatedlywritten in the four DMAs for its protection. Each DMA has two blockshaving 32 sectors in total, i.e., one block has 16 sectors. Each DMA hasa PDL (Primary Defect List) which is a primary data storage and an SDL(Secondary Defect List) which is secondary data storage. In general, thePDL contains entries of defects that occurred during fabrication of thedisk, and all defective sectors identified during formatting, i.e.,initializing and re-initializing, of the disk. On the other hand, theSDL, which is organized in block units, contains entries of defectiveareas that occurred after the formatting, or defective areas that cannotbe listed on the PDL during the formatting. The defective areas (i.e.,defective sectors or defective blocks) in the data area are replacedwith good areas, according to a slipping replacement algorithm or linearreplacement algorithm.

FIG. 2A depicts a circumstance in which the slipping replacementalgorithm is applied to a defective area listed on the PDL. If thedefective sector is present in the user area on which actual data is tobe written, then the defective sector is skipped. The defective sectoris replaced with a good sector next to the defective sector.

FIG. 2B depicts a circumstance in which the linear replacement algorithmis applied to a defective area listed on the SDL. If the defective blockis present in the user area or the spare area, then the defective blockis replaced with block units of replacement areas assigned to the sparearea.

FIG. 3 illustrates a block diagram showing one example of a recordingportion of a related art optical recording medium recording/reproductiondevice. It is provided with an optical pickup for writing/reading datato/from an optical recording medium, a pickup servo unit for controllingthe optical pickup to maintain a distance between an objective lens inthe optical pickup and the optical disk and for tracking a pertinenttrack, a data processor for processing and providing an input data tothe optical pickup, an interface for exchanging data with an externalhost, and a microcomputer for controlling the above units. A host isconnected to the interface of the device for recording/reproducing datato/from an optical recording medium for exchange of command and data.

Referring to FIG. 4, when data to be written is provided to the host,the host then provides the data to be written together with a writecommand to the device for recording/reproducing data to/from an opticalrecording medium. In this instance, the device for recording/reproducingdata to/from an optical recording medium writes no data on defectiveareas utilizing the PDL and the SDL. That is, physical sectors listed onthe PDL are skipped in the writing. As shown in FIG. 4, physical blocksb1kA and b1kB (listed on the SDL) are replaced with replacement blocksb1kE and b1kF assigned to the spare area in the writing. If a defectoccurs again in a replacement block b1kG (that was intended to replacethe defective block b1kC), a new replacement block b1kH in the sparearea is assigned to the defective block b1kC for writing the data. And,during a writing or reading operation, if a defective block isdiscovered that is also not listed on the SDL, then a replacement blockis located in the spare area, the data on the defective block is writtenthereon again, and positional information on the defective block arelisted on the SDL entry for protection of the data. Instead of adefective block, if a block having a high possibility of causing anerror is discovered during a writing or reading operation, then thisblock is treated as if it were a defective block in the manner justdescribed. Thus, not only blocks with defects, but also blocks with ahigh possibility of causing errors, for example, blocks error thereoncan be corrected are subjected to linear replacement, for protection ofdata.

However, the aforementioned DVD-RAM has the problem of a reducedrecording capacity caused by the spare areas allocated in a diskfabrication process for protection of data. And, because the size of thespare areas are fixed in advance without regard to the actual defectivestate of the disk, the spare areas are used inefficiently. In mostinstances, the disk management technique will not use entire spareareas. Also, if the total number of defective sectors for a block islarger than the total number of spare areas, all of the defectivesectors cannot be replaced. This causes the disk management technique tofail. In this instance, the system will treat the disk as fatallydefective, and the disk will no longer be used.

A CD-RW is one of the rewritable optical recording media. It managesdefective sectors only when the defect is fatal, but does not managecorrectable errors. The data protection provided by the CD-RW is notadequate.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for managinga defective area of an optical recording medium that substantiallyobviates one or more of the problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a method for managing adefective area of an optical recording medium, which can make arecording capacity larger while protecting data.

Another object of the present invention is to provide a method formanaging a defective area of an optical recording medium, which canstore and manage positional information of a defective area encounteredduring data writing/reading separately from file information.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the methodfor managing a defective area on an optical recording medium being readby a recording/reproducing device, the recording/reproducing devicebeing controlled by a control unit, the recording/reproducing devicereproducing data from the optical recording medium and providing thedata to the control unit the method comprising:

(A) returning information on a newly-discovered defective area to thecontrol unit when the defective area is encountered during reading bythe recording/reproducing device of data recorded on an opticalrecording medium;

(B) causing the data intended for the defective area to be written bythe recording/reproduction device in another area under the control ofthe control unit; and

(C) causing positional information about the defective area to bewritten by the recording/reproducing device in the user area under thecontrol of the control unit.

The positional information on the defective area is managed in sectorunits.

In the other aspect of the present invention, there is provided a methodfor managing a defective area on an optical recording medium beingwritten to be a recording/reproducing device, the recording/reproducingdevice being controlled by a control unit, the control unit generating acontrol signal when data is to be written and providing a first controlsignal together with the data to be written to the recording/reproducingdevice for writing the data at a position designated by the firstcontrol signal the method comprising:

(A) stopping the writing by the recording/reproducing device if adefective area is encountered during the writing and returninginformation on the defective area to the control unit;

(B) generating a second control signal when the information on thedefective area is received and providing the second control signal tothe recording/reproducing device together with the data to be written;

(C) determining if any other defective area is present while writing thedata in response to the second control signal from the control unit andreturning to step (A) if the defective area is present to repeat steps(A) and (B), and or continuing to write the data if no other defectivearea is present; and

(D) writing the positional information on the one or more defectiveareas on a particular position of the user area.

The control signal is generated such that no data is written, not onlyon areas listed on the file information, but also on the defective areaslisted on a particular position of the data area.

File information in the ICB concerning a file is interspersed withinformation about at least one defective area.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 illustrates a structure of a related art optical disk;

FIG. 2A illustrates a general slipping replacement method according tothe related art;

FIG. 2B illustrates a general linear replacement method according to therelated art;

FIG. 3 illustrates a block diagram of a general optical diskrecording/reproducing device according to the related art;

FIG. 4 illustrates data writing on a general optical disk using a linearreplacement of SDL according to the related art;

FIG. 5 illustrates a structure of an optical disk in accordance with apreferred embodiment of the present invention;

FIG. 6 illustrates a flow chart showing a method for managing adefective area of an optical recording medium during reading inaccordance with a preferred embodiment of the present invention;

FIG. 7 illustrates data writing with a defective area replaced withother area in an optical disk of the present invention;

FIG. 8A illustrates a UDF file system on file 1 when no defect hasoccurred in an optical disk of the present invention;

FIG. 8B illustrates a UDF file system on file 1 when a defect hasoccurred in an optical disk of the present invention; and,

FIG. 9 illustrates a flow chart showing a method for managing adefective area of an optical recording medium during recording inaccordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. FIG. 5 illustrates a structure of an optical disk inaccordance with a preferred embodiment of the present invention, whereina data area (also known as a user area) has no spare areas, rather onlyan area for recording actual data. The data area may be managed zone byzone. And, since there is no spare area, no SDL is required in the DMAsin the lead-in area and in the lead-out area. The present inventionreplaces a defective area within a data Management of the defective areais accomplished via a file system, thus preventing a reduction of arecording capacity in the manner suffered as a problem of the relatedart discussed above.

FIG. 6 illustrates a flow chart showing a method for managing adefective area of an optical recording medium during reading inaccordance with a preferred embodiment of the present invention.

Referring to FIG. 6, when a user selects reproduction, the hostgenerates a read command with reference to file information in a filesystem, and provides it to the optical disk recording/reproductiondevice (step 601). The read command contains an LBA (Logical BlockAddress) which designates a starting position and a transmission length,thus defining the size of the data. If the file system for file 1, whichis desired to be read, is as shown in FIG. 8A, then the host issues aread command to read N sectors of data starting from address A within auser/data area.

Then, the optical disk recording/reproduction device reads data as thehost has designated, i.e., N sectors starting from address A (step 602).It provides the read-out data to the host (step 603). And, then, itprovides a command execution report to the host (step 604).

If a defective block is encountered within a section that the hostdesignated, i.e., within a section from the sector having address A tothe sector having address B, the optical disk recording/reproductiondevice also includes this information in the command execution report.The above defective block, not listed yet, can include not only afatally defective block, but also a defective block of which the defectis correctable.

The host determines whether the command execution report includesinformation on the defective area (step 605). If the command executionreport has information only on good states, then this implies that thereare no defective blocks among the N sectors. But, if the commandexecution report includes information about bad states, then thisimplies that the command execution report has information on defectiveareas. Therefore, if it is determined in step 605 that the commandexecution report has information on a defective area, then the hostprovides data about the defective block together with the write commandto the optical disk recording/reproduction device (step 606). Theoptical disk recording/reproduction device then writes the data aboutthe defective block at a position in the user/data area designated bythe write command (step 607).

The position the write command designates is an arbitrary position inthe data area (also known as the user area), because there is no sparearea employed in the present invention. For example, referring to FIG.7, if defects are encountered in L sectors starting from address E, thendata read from blocks in the L sectors are written to a replacementgroup of L sectors starting from address C under the control of thehost. Since defects encountered during a write/read operation areprocessed in ECC block units, the value of L is a multiple of 16.Thereafter, positional information on the defective blocks is written toparticular positions within the data area (step 608). This prevents thedefective blocks from being written to or read from again.

If the file management is conducted as a UDF (Universal Disc Format)file system, then the positional information of the defective blocks isadded to a non-allocatable spare list within the data area in the step608. Because a rewritable optical disk takes all blocks with defects asdefective blocks, the positional information on the defective blockswritten on the non-allocatable spare list is in block units. That is,the positional information about the defective blocks is represented bya first sector number of each defective block. The optical diskrecording/reproduction device treats the designated sector and the next15 sectors as defective.

If a defect occurs at a block within the non-allocatable spare list,then the non-allocatable spare list is written according to theforegoing process, with the non-allocatable spare list being written toanother block in the data area. In this instance, the positionalinformation of the defective block is also added to the non-allocatablespare list. Thus, a position of the non-allocatable spare list may bechanged within the data area, which may be found using an anchor point.

An anchor point is a logical sector number (LSN). Typically, it isduplicated by being written at address 256 and at an end sector of thedata area. Any defects that occur at these positions cannot be replacedwith other areas. In the UDF file system, all files and directories aremanaged depending on the anchor point. If there is a defect at theanchor point, the disk is no longer usable.

To protect the anchor point, a few duplicate areas (for example, around10 sectors) may be assigned within the data area to redundantly writethe anchor point. The points of duplication are scattered to many places(for example, zone by zone) as a countermeasure, e.g., against bursterror and the like. Because file information is changed, if data for adefective block is written on other block in the data area to replacethe defective block, then the file system is also corrected (step 609).

If the file management is conducted according to the UDF file system,and a replacement is made as shown in FIG. 7, an ICB (InformationControl Block) showing file starting positions and file sizes iscorrected as shown in FIG. 8B. That is, the ICB is initially as shown inFIG. 8A. The file 1 is recorded starting from the sector at address Aand continuing for N sectors at the time of issuing the read command.FIG. 8B depicts the ICB representation of how the file is recorded afterdiscovery of the defective area. In FIG. 8, the file 1 is recordedstarting from the sector having address A and continuing for N1 sectors,with an interruption in the file starting at the sector having address Cfor L sectors, and resuming at the sector having address F for N2sectors, where N=N1+N2. Consequently, three read commands may berequired to read file 1 the next time, e.g., read commands for readingN1 sectors starting from address A, reading L sectors starting ataddress C, and for reading N2 sectors starting at address F. Once datato be written is provided, the host issues the write command withreference to the positional information of the defective blocks listedin the non-allocatable spare list and the ICB.

FIG. 9 illustrates a flow chart showing a method for managing adefective area of an optical recording medium during recording inaccordance with a preferred embodiment of the present invention.

Referring to FIG. 9, when data to be written is generated, the hostprovides the data to be written to the optical diskrecording/reproducing device, together with a write command (step 901).In this instance, the host issues the write command such that no data iswritten to areas listed on the ICB, nor to the defective blocks listedon the non-allocatable spare list using the positional information aboutdefective areas listed on the ICB and the non-allocatable spare list.Then, the optical disk recording/reproducing device checks (step 903) ifthere is a defective area while recording input data starting from aposition that the write command designates (step 902).

Because the write command is issued such that no data is written toknown defective areas, the defective areas are newly found defectiveareas, including, not only fatally defective blocks, but also defectiveblocks of which the defects are correctable. If it is determined that nodefective blocks are encountered in step 903, then the data writingoperation is continued until it is completed. But if it is determinedthat a defective block is encountered in step 903, then the writecommand is interrupted and information about the defective area isreturned to the host (step 904). Upon reception of the information aboutthe newly discovered defective area, the host provides a new writecommand and data to the optical disk recording/reproducing device (step905). The new write command is generated such that no data is written tothe newly-discovered defective area.

For example, if the write command of step 901 is to write N sectors ofdata starting from address A, and if a defect is encountered at a sectorhaving address E, the write command is stopped and information about thenewly-discovered defective block is returned to the host. The host mayissue a new write command to write the data starting from a sectorhaving address F. Accordingly, the optical disk recording/reproducingdevice writes new data from the host starting from the sector havingaddress F as designated by the new write command (step 906).

The optical disk recording/reproducing device keeps on checking for thepresence of defective areas while writing data at the position that thenew write command designates (step 907). If another new defective areais encountered again, the process proceeds back to step 904, to repeatthe foregoing steps. Otherwise, the data writing operation continues,starting at the position the write command designates, until completion(step 908).

If it is determined that the writing is completed in step 908, then theoptical disk recording/reproducing device writes positional informationabout the defective area at a particular position within the data areathat is determined by the host. The positional information on thedefective area may be written whenever the write command ends, or at atime after the writing is completed.

If the file system is of the UDF, then the positional information aboutthe defective area is added/written to the non-allocatable spare list.Or, if data is written as shown in FIG. 7 according to the writecommand, then file information is written out on an ICB as shown in FIG.8B (optional step 910). Again, FIG. 8B illustrates a case when a writecommand to write N sectors of data starting from a sector having anaddress A encounters a defective area of L sectors beginning at addressC. Thus, the ICB represents N1 sectors that are separated from N2sectors by defective block of L sectors. The positional informationabout the defective area is managed separately from the fileinformation, conferring the advantage that the positional informationabout the defective area will remain after the file information changes.This prevents the host from attempting to write or read data to/from thedefective block.

The positional information about the defective block on thenon-allocatable spare list may be newly stored in sector units dependingon formatting. If there is a PDL in a DMA, of the defective blocks onthe non-allocatable spare list, only sectors having defects aretransferred to the PDL, while the positional information on thedefective blocks is erased from the non-allocatable spare list. If thereis no DMA, only information about the defective sectors should be listedon the non-allocatable spare list while the positional information aboutthe defective blocks may be erased, in the situation where thepositional information on the defective blocks and the positionalinformation on the defective sectors are written such that they can bedistinguished from each other. To do this, one bit may be used.

As has been explained, the method for managing a defective area of anoptical recording medium of the present invention has the followingadvantages.

First, the reduction in recording capacity due to the provision of spareareas according to the related art can be avoided and efficiency interms of use of the disk can be improved for a rewritable opticalrecording medium by replacing a defective block with another blockwithin the data area only when a defect is encountered and making a filesystem to manage the defective areas. That is, while protecting datawith an effect identical to a linear replacement, the recording capacitycan be increased.

Second, a life time of the disk can be prolonged because there is nolimitation on a size of the available replacement block. This permitsdata to be written regardless of a number of defective sectors.

Third, since the positional information on the defective area is managedseparately from the file information, this permits the positionalinformation about the defective area to remain even after the fileinformation is changed. This prevents a mistake of writing/reading datato/from the defective block.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method for managing adefective area of an optical recording medium of the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method for managing a defective area on a storage medium, themethod comprising: (A) identifying a defective area found duringrecording or reproducing of data; (B) writing the data intended for thedefective area in any part of a user area that is unused, wherein thestorage medium is without any pre-designated spare area so that theentire user area corresponds to an entire data area of the storagemedium; and (C) writing positional information about the defective areain the user area.
 2. The method of claim 1, further comprising: updatingfile information concerning the positional information about thedefective area.
 3. The method of claim 1, further comprising: correctinginformation in an information control block (ICB) concerning thepositional information about the defective area.
 4. The method of claim3, wherein information in the ICB concerning a file is interspersed withinformation on at least one defective area.
 5. The method of claim 3,wherein, for file information managed according to a Universal DiscFormat (UDF) file system, a plurality of sectors are allocated forprotection of an anchor point.
 6. The method of claim 5, wherein theplurality of sectors allocated to the anchor point are assigned to theuser area and are dispersed within the user area.
 7. A method formanaging a defective area on a storage medium, the storage medium havinga user area thereon, the method comprising: (A) outputting informationon a newly-discovered defective area when the defective area isencountered during a recording mode or reading mode; (B) causing thedata intended for the defective area to be written in any part of theuser area that is unused, wherein the storage medium is without anypredesignated spare area so that the entire user area corresponds to anentire data area of the storage medium; and (C) writing positionalinformation about the defective area in a specific area of the userarea.
 8. The method of claim 7, further comprising: correctinginformation in an information control block (ICB) concerning thepositional information about the defective area.
 9. The method of claim8, wherein information in the information control block (ICB) concerninga file is interspersed with information on at least one defective area.10. The method of claim 8, wherein, for file information managedaccording to a universal disc format (UDF) file system, a plurality ofsectors are allocated for protection of an anchor point.
 11. The methodof claim 10, wherein the plurality of sectors allocated to the anchorpoint are assigned to the user area and are dispersed within the userarea.
 12. The method of claim 7, wherein the positional informationabout the defective area is managed in sector unit.
 13. The method ofclaim 12, wherein the information about defects in sector units isrecorded in a lead-in area.
 14. The method of claim 12, wherein theinformation about defects in sector units is recorded in the user area.15. The method of claim 12, wherein the information about defects insector units is recorded in a non-allocatable spare list located in theuser area, and can be distinguished from information about defects inblock units.
 16. A storage medium without any pre-designated spare areaso that an entire user area corresponds to an entire data area of thestorage medium, wherein the storage medium includes a defect managementinformation for indicating a position about a defective area in the userarea.
 17. The storage medium of claim 16, wherein the storage mediumfurther includes a file information concerning the positionalinformation about the defective area.
 18. The storage medium of claim16, wherein the storage medium further includes information in aninformation control block (ICB) concerning the positional informationabout the defective area.
 19. The storage medium of claim 18, whereininformation in the ICB concerning a file is interspersed withinformation on at least one defective area.
 20. The storage medium ofclaim 18, wherein, for file information managed according to a UniversalDisc Format (UDF) file system, a plurality of sectors are allocated forprotection of an anchor point.
 21. The storage medium of claim 20,wherein the plurality of sectors allocated to the anchor point areassigned to the user area and are dispersed within the user area.